Pyrotechnic-actuated folding fin assembly



Feb. 14, 1967 J. E. WEIMHOLT ETAL 3,304,030

FYROTEGHNIC-ACTUATED FOLDING FIN ASSEMBLY Filed Sept. 24, 1965INVENTORS. JAMES E. WElMHOLT ATTORNEY.

LAWRENCE M. BIGGS,JR.

United States Patent 3,304,030 PYROTECHNIC-ACTUATED FOLDING FIN ASSEMBLYJames E. Weimholt and Lawrence M. Biggs, Jr., China Lake, Califi,assignors to the United States of America as represented by theSecretary of the Navy Filed Sept. 24, 1965, Ser. No. 490,143 6 Claims.(Cl. 2443.28)

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

The present invention relates to a folding fin assembly for an aerialmissile and more particularly to means for effecting in-fiight erectionof the fins in a positive and reliable manner.

Folded fin assemblies have been employed on various types of aerialmissiles in the interests of space limitations during storage in amagazine and carriage on an aircraft. Such assemblies have relied uponaerodynamic forces or used spring-loaded devices to effect erectionafter launching from the aircraft and have the disadvantage that thefins do not always unfold simultaneously with the result that the flightof the missile is unstable.

It is therefore a purpose and object of this invention to provide afolding fin assembly having spatial and other advantageous featureswhile in storage or attached to the aircraft, yet also possessingaerodynamically advantageous features of large caliber stabilizing finsupon launching of the missile.

Another object is the provision of means for unfolding the fins in arapid, positive and reliable manner.

A further object is to provide a folding fin assembly which is simple inconstruction, economical to manufacture and is reliable in its manner ofoperation.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunctio with the accompanying drawings wherein:

FIG. 1 is a vertical elevation of the folding fin assembly of thisinvention, with parts broken away to illustrate certain structuraldetails;

FIG. 2 is an end elevation of the assembly looking in the direction ofthe arrow 2, FIG. 1; and

FIG. 3 is a view similar to FIG. 1 but showing the fins in erect orunfolded position.

Referring now to the drawings, there is shown in FIG. 1 a folding finassembly attached to the aft end of a missile body 12, shown only inpart. The assembly 10 comprises an attaching band 14 and an aft plate 16interconnected by a plurality of fin housings 18.

Each housing 18 comprises a pair of elongated, generally triangularmounting plates 20 disposed spacedapart and generally parallel to thelongitudinal axis of the assembly and suitably secured at their fore andaft ends to band 14 and plate 16, as by welding or the like. Each pairof plates 20 has secured thereto at its forward portions a fairing plate22.

Plate 16 is disposed substantially perpendicular to the longitudinalaxis of the assembly and is provided with extensions or tabs 24, therebeing one such tab for each housing 18 into which the tab extends, for areason hereinafter appearing, and which is secured to the rear ends ofplates 20 thereof. Adjacent to plate 16, each housing 18 has a pivot pin26 upon which is pivotally mounted a cam block 28. Each cam block isformed with a curved cam surface 30 and a shoulder 32 and carries a finblade 34, the shoulder 32 engaging with the outer end 35 of the tab 24associated therewith when the cam block has pivoted and the fin bladehas been unfolded to erect position; see FIG. 3. Pins 34 may be retainedin folded position by 3,304,030 Patented Feb. 14, 1967 "ice means ofshear-pins 36, force-fitted into holes 37 in cam blocks 28.

The means for erecting the fin blades comprises an expandable chamber 38including a pair of telescoping cuplike members 40 and 42, member 40being suitably secured to aft plate 16 centrally thereof and extendingforwardly, member 42 closing off the open end of member 40 and carryinga conventional gas generating pyrotechnic device 44 such as a cartridgeor the like. Slidably mounted on member 42 is a sleeve 46 forming partof a pusher assembly comprising pusher arms 48 rigidly secured to thesleeve, member 42 being formed with a lip 50 for engaging sleeve 46 andmoving the same. Each arm 48 is formed with a pusher element or finger52 having a facing 54. The number of arms 48 is the same as the numberof housings 18 with a pusher finger disposed adjacent the curved surface30 of each cam block 28 when the fin blade associated therewith is inits folded position; FIG. 1.

For aerodynamic reasons, it is desirable to close the open spacesbetween housings 18 with sections 56 of metallic skin or the likesecured to the attaching band 14, the aft plate 16 and plates 20 byscrews 58 of the like, plates 20 being provided at their inner edgeswith narrow strips 60 extending laterally sufficiently to formsupporting ledges for the adjacent edges of sections 56; FIG. 2.

Attaching band 14 may be secured to the missile body 12 by any suitablemeans. Such means may take the form, if desired, of a plurality of pairsof circumferentially spaced projections 62 on the inner periphery of theband 14, each pair of projections 62 being adapted to receivetherebetween one of a plurality of circumferentially-spaced projections64 on the body 12. In attachmerit, the fin assembly is slipped over therear end of body 12 so that projections 64 are disposed in thecircumferential spaces between pairs of projections 62 after which theassembly is rotated slightly to have the pairs of projections 62 receivethe projections 64 and then locked in place.

In operation, the missile is launched and as it falls away from theaircraft the pyrotechnic device 44 is activated, the gas generatedexpanding chamber 38 and imparting movement to member 42, sleeve 46 andarms 48. Facings 54 on fingers 52 engage curved surfaces 30 of the camblocks 28 and swing the blocks and fin blades 34 attached thereto to theunfolded or erect position. Facing 54 on each finger 52 is of arelatively hard material, for example, steel, while the material of eachblock 28 is relatively softer, for example, aluminum, and the structuraldimensions are so chosen that in the unfolded position the facings wedgeand dig into the respective cam blocks, thus locking the fin blades inerect position and arresting movement of the pusher assembly and member42. The energy imparted to member 42 may be predetermined by selectionof a pyrotechnic device 44 having an energy output of desiredproportions and adjusted by the location of perforations 66 in member 40which vent the gas in chamber 38 to the atmosphere as they are uncoveredby movement of member 42.

There has thus been provided a folding fin assembly in which the finsare erected simultaneously in a rapid, positive and reliable manner.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. An unitary folding fin assembly comprising:

a circular plate;

a plurality of radially extending tabs on said plate arrangedequi-angularly around the periphery thereof;

a plurality of fin housings, each comprising a pair of parallel mountingplates having rear ends disposed on either side of one of said tabs andsecured thereto;

an attaching band disposed generally parallel to said circular plate andsecured to the front portions of said mounting plates;

a plurality of pivot pins, one per fin housing supported in the mountingplates thereof adjacent the associated tab;

a plurality of cam blocks, one per pivot pin and supported thereon forswinging from a folded position to an erect position in which swingingis limited by engagement of the block with the end of the associatedtab;

a plurality of fins, one per cam block and secured thereto for swingingtherewith from folded to erect position; and

means engaging said cam blocks for swinging the same and the fins toerect position.

2. The fin assembly of claim 1, wherein said means comprises:

an unitary pusher structure disposed between said fin housings andhaving a plurality of pusher fingers, one per cam block and engageabletherewith for swinging the same upon movement of the structure;

an expandable chamber supported on said circular plate and having amovable part carrying said pusher sup port structure; and

gas generating means in said chamber for expanding the same andimparting movement to said movable part.

3. The fin assembly of claim 2, wherein:

each said pusher finger is provided with a facing of a material harderthan the material of the associated cam block and is dimensioned so thateach facing digs into its associated cam block after said block has beenswung to erect position for locking the blocks and fins in erectposition.

4. A folding fin assembly for an aerial body comprising:

an attachment means adapted to receive one end of said body;

a plurality of fin housings secured to said attachment means andextending rearwardly therefrom;

transverse means secured to said housings at the rear ends thereof;

each housing pivotally mounting a cam block, respectively;

each cam block carrying a fin disposed wholly within its respectivehousing when said fin is in folded position;

an expandable chamber mounted centrally of said transverse means andhaving a forwardly movable part;

a structure carried by said part and movable thereby;

a plurality of pusher elements rigid with said structure, there beingone element per cam block and engageable therewith for swinging the sameand the fin carried thereby from unfolded to erect position; and

pyrotechnic means in said chamber for expanding said chamber and movingsaid part and structure for swinging said cam blocks and associated finsto erect position.

5. The fin assembly of claim 4, wherein:

each of said pusher elements is of a material that is harder than thematerial of the cam block associated therewith,

6. In combination with an elongated aerial body having a longitudinalaxis, a folding fin assembly comprising:

an attaching band attached to the rear end of said body;

a circular support plate disposed rearwardly of said band with saidlongitudinal axis passing through the center thereof perpendicularthereto;

a plurality of fin housings arranged around said band and plate, eachhousing including a pair of mounting plates rigidly secured at theirfront and rear ends to said band and support plate, respectively;

a plurality of pivot pins, one per housing and supported in the mountingplates thereof adjacent said support plate;

a plurality of fin members, one per housing and pivotally mounted on thepivot pin thereof for swinging from a folded position with the finmember disposed wholly within the housing to an erect position with amajor portion of the fin member outside the housa plurality of rigidlyinterconnected radially-etxending arms mounted on said support plate foraxial movement forwardly thereof;

the number of arms being equal to the number of fin members andassociated therewith so that the radial end of each arm is engageablewith its associated fin member for swinging the same to erect positionin response to forward movement of said arms; and

means for imparting forward movement to said arms.

References Cited by the Examiner UNITED STATES PATENTS 1,181,203 5/1916Alard 2443.28 2,671,398 3/1954 Peck 102-2, 2,821,924 2/1958 Hansen et al244-3.28

References Cited by the Applicant UNITED STATES PATENTS 2,977,880 4/1961 Kershner. 3,010,677 11/1961 Guthrie et al. 3,057,589 10/1962Nutkins et a1. 3,103,886 9/1963 Popenoe. 3,125,956 3/ 1964 Kongelback.3,127,838 4/1964 Moratti et al. 3,165,281 1/ 1965 Gohlke.

BENJAMIN A. BORCHELT, Primary Examiner.

' V. R, PENDEGRASS, Assistant Examiner,

1. AN UNITARY FOLDING FIN ASSEMBLY COMPRISING: A CIRCULAR PLATE; APLURALITY OF RADIALLY EXTENDING TABS ON SAID PLATE ARRANGEDEQUI-ANGULARLY AROUND THE PERIPHERY THEREOF; A PLURALITY OF FINHOUSINGS, EACH COMPRISING A PAIR OF PARALLEL MOUNTING PLATES HAVING REARENDS DISPOSED ON EITHER SIDE OF ONE OF SAID TABS AND SECURED THERETO; ANATTACHING BAND DISPOSED GENERALLY PARALLEL TO SAID CIRCULAR PLATE ANDSECURED TO THE FRONT PORTIONS OF SAID MOUNTING PLATES; A PLURALITY OFPIVOT PINS, ONE PER FIN HOUSING SUPPORTED IN THE MOUNTING PLATES THEREOFADJACENT THE ASSOCIATED TAB; A PLURALITY OF CAM BLOCKS, ONE PER PIVOTPIN AND SUPPORTED THEREON FOR SWINGING FROM A FOLDED POSITION TO ANERECT POSITION IN WHICH SWINGING IS LIMITED BY ENGAGEMENT OF THE BLOCKWITH THE END OF THE ASSOCIATED TAB; A PLURALITY OF FINS, ONE PER CAMBLOCK AND SECURED THERETO FOR SWINGING THEREWITH FROM FOLDED TO ERECTPOSITION; AND MEANS ENGAGING SAID CAM BLOCKS FOR SWINGING THE SAME ANDTHE FINS TO ERECT POSITION.